Solubility prediction of CO2, CH4, H2, CO and N2 in Choline Chloride/Urea as a eutectic solvent using NRTL and COSMO-RS models

Deep eutectic solvents (DESs) have received much attention as a potential extracting agent in recent years due to favorable characteristic such as low cost, non-toxic, non-flammable and availability. In this research, the solubility of different gases including CO2, CO, CH4, H2 and N2 in Choline Chloride/Urea as a deep eutectic solvent at the temperature ranging from 308 and 333 K and pressure up to 5 MPa is determined. Furthermore, the effect of different molar ratios of Choline Chloride to Urea (1:1.5, 1:2.0 and 1:2.5) on the solubility of CO2 is elucidated. In this regard, two thermodynamic models (NRTL and COSMO-RS) are used. The performance of the proposed models is validated with the experimental data. The adjustable parameters of NRTL model are computed by local optimization. In order to comprise the results of two thermodynamic models precisely, the absolute relative errors (ARDs) are computed. The results indicate that NRTL model predicts the solubility data superior than COSMO-RS model. This is rationalized because COSMO-RS model does not use any adjustable parameters in solubility calculation.